<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>media</title>
</head>
<style>
    .container {
        position: relative;
    }
    li {
        display: list-item;
    }
    @media screen and (min-width: 600px){
        nav {
            float: left;
            width: 25%;
            border: blue 1px solid;
        }
        section {
            margin-left: 25%;
            border: yellow 1px solid;
        }
    }
    @media screen and (max-width:599px) {
        nav li {
            display: none;
        } 
    }
</style>
<body>
    <div class="container">
            <nav>
                <li>设备</li> 
                <li>位置</li>
                <li>用户</li>
            </nav>
            
            <section>
                第一段
                <p>MID</p>
            </section>
            <section>
                第二段
                <p>mid</p>
            </section>
            <section>
                第三段
                <p>mid</p>
            </section>
        </div> 
</body>
</html>